Radar and radio frequency band designations
A frequency band designation is a short name for a slice of spectrum, and three systems are in use. IEEE radar letters (L, S, C, X, Ku, K, Ka, V, W), ITU band numbers (VHF, UHF, SHF …) and NATO letters (A to M). They clash: IEEE K is 18–27 GHz, NATO K is 20–40 GHz. Enter a frequency to see all three.
Any frequency from 3 MHz to 300 GHz shows in all three systems. 24 GHz is the K-band speed-radar frequency.
- K-band warning: IEEE K is 18–27 GHz, NATO K is 20–40 GHz and also covers IEEE Ka. Always say which system you mean.
One logarithmic frequency ruler from 3 MHz to 300 GHz with the three systems stacked: IEEE radar letters on top, ITU bands in the middle, NATO letters at the bottom. The green frames mark the band your frequency falls in, and the vertical green line marks the frequency itself. The amber hatching marks IEEE K and NATO K, so you can see how far apart two bands with the same letter are. Labels too wide for their box sit outside it on a short leader line. Frequencies follow the unit of the frequency field.
Band edges are designations, not allocations. A frequency being “in X-band” says nothing about who may transmit there, which the national frequency plan decides. NATO letters are shown from A to M only, ITU bands from 4 to 12.
All three band systems
The same spectrum, cut three ways. The rows of one table do not line up with the rows of the next, because the edges differ. Your current band is highlighted in each table.
IEEE Std 521 radar letters
| Band | Range |
|---|---|
| HF * | 3–30 MHz |
| VHF * | 30–300 MHz |
| UHF * | 300–1000 MHz |
| L | 1–2 GHz |
| S | 2–4 GHz |
| C | 4–8 GHz |
| X | 8–12 GHz |
| Ku | 12–18 GHz |
| K | 18–27 GHz |
| Ka | 27–40 GHz |
| V | 40–75 GHz |
| W | 75–110 GHz |
| mm | 110–300 GHz |
* HF, VHF and UHF from IEEE Std 521-2002, via Wikipedia.
ITU bands (RR Art. 2, ITU-R V.431)
| Band | Name | Range |
|---|---|---|
| 4 VLF | Very low frequency | 3–30 kHz |
| 5 LF | Low frequency | 30–300 kHz |
| 6 MF | Medium frequency | 300 kHz–3 MHz |
| 7 HF | High frequency | 3–30 MHz |
| 8 VHF | Very high frequency | 30–300 MHz |
| 9 UHF | Ultra high frequency | 300 MHz–3 GHz |
| 10 SHF | Super high frequency | 3–30 GHz |
| 11 EHF | Extremely high frequency | 30–300 GHz |
| 12 THF | Tremendously high frequency | 300 GHz–3 THz |
NATO letters (A–M)
| Band | Range |
|---|---|
| A | 0–250 MHz |
| B | 250–500 MHz |
| C | 500–1000 MHz |
| D | 1–2 GHz |
| E | 2–3 GHz |
| F | 3–4 GHz |
| G | 4–6 GHz |
| H | 6–8 GHz |
| I | 8–10 GHz |
| J | 10–20 GHz |
| K | 20–40 GHz |
| L | 40–60 GHz |
| M | 60–100 GHz |
How it works
- 01
Enter the frequency
Type it in MHz or GHz. The page looks the frequency up in three tables at once and draws it on a ruler that covers 3 MHz to 300 GHz.
- 02
Read the IEEE radar letter
IEEE Std 521 gives the letters radar engineers use: L 1–2 GHz, S 2–4, C 4–8, X 8–12, Ku 12–18, K 18–27, Ka 27–40, V 40–75 and W 75–110 GHz, then the millimetre-wave band up to 300 GHz. Below 1 GHz it uses HF, VHF and UHF.
- 03
Read the ITU band number
The ITU cuts the spectrum into decades. Band N runs from 0.3·10N to 3·10N Hz, so N = ⌊log10(f / 0.3)⌋ with f in Hz. Band 9 is UHF (300 MHz to 3 GHz) and band 10 is SHF (3–30 GHz).
- 04
Read the NATO letter
The NATO scheme runs from A (up to 250 MHz) to M (60–100 GHz) in plain alphabetical order. It reuses IEEE letters for other bands. NATO C is 0.5–1 GHz, IEEE C is 4–8 GHz.
- 05
Watch the edges
A frequency exactly on an edge belongs to the upper band here, so 12 GHz is Ku and 3 GHz is band 10. The ITU Radio Regulations put an exact edge in the lower band. That matters only at the edge frequency itself.
Formulas
- N — ITU band number, 4 (VLF) to 12 (THF)
- f — frequency, Hz
- band N spans 0.3·10N to 3·10N Hz
- λ — free-space wavelength, m
- c — speed of light, 299 792 458 m/s
Worked example
- IEEE: 18 GHz ≤ 24 GHz < 27 GHz → K
- ITU: N = ⌊log10(24×109 / 0.3)⌋ = ⌊10.90⌋ = 10 → SHF (3–30 GHz)
- NATO: 20 GHz ≤ 24 GHz < 40 GHz → K
- λ = 299 792 458 / 24×109 = 12.49 mm
- → IEEE K and NATO K agree here. At 35 GHz they part: IEEE Ka, NATO K
FAQ
- What band is 24 GHz?
- IEEE K-band (18–27 GHz), ITU band 10 (SHF, 3–30 GHz) and NATO K-band (20–40 GHz). The 24.05–24.25 GHz slot is where K-band speed radars work, with a nominal 24.150 GHz in the NHTSA specification.
- Why is K-band so confusing?
- Because two systems use the same letter for different bands. IEEE K is 18–27 GHz, with Ku below it and Ka above. NATO K is 20–40 GHz, which takes in most of IEEE K and all of IEEE Ka. 35 GHz is therefore Ka in IEEE terms and K in NATO terms. NATO C (0.5–1 GHz) and IEEE C (4–8 GHz) clash the same way, and so do NATO L (40–60 GHz) and IEEE L (1–2 GHz). Always name the system.
- What do the ITU band numbers mean?
- Each number is one decade of spectrum. Band N spans 0.3·10N to 3·10N Hz, so band 9 (UHF) is 300 MHz to 3 GHz and band 10 (SHF) is 3–30 GHz. The ITU Radio Regulations define nine bands, 4 (VLF) to 12 (THF), and ITU-R V.431 adds the metric names such as decimetric and centimetric waves.
- Where do the radar letters come from?
- From the Second World War, when letters hid the real frequencies of radar sets. IEEE Std 521 fixed them as a standard, first in 1976, and the 2019 edition is current. It also calls 110–300 GHz the millimetre-wave band, while acknowledging that popular usage means 30–300 GHz.
- Which band does a frequency exactly on an edge belong to?
- Here, to the upper band. 12 GHz reads Ku, 3 GHz reads ITU band 10 and NATO F. The ITU Radio Regulations count the upper edge into a band and leave the lower edge out, so they would put 3 GHz into band 9. The difference only ever affects the edge frequency itself, and this page flags it when you hit one.
The band sets how a signal bends, scatters and gets absorbed, but whether it reaches still depends on the hills in between. Waveshed draws line of sight and coverage over real elevation data, free in your browser.
Check the coverage →Sources & further reading
- Recommendation ITU-R V.431 — Nomenclature of the frequency and wavelength bands used in telecommunications ↗ — band numbers and names, in force as V.431-9 (10/2025)
- Radio Regulations — ITU ↗ — Article 2 divides the spectrum into nine bands, numbers 4 to 12
- IEEE Std 521-2019 — IEEE Standard Letter Designations for Radar-Frequency Bands — the radar letters L to W and the 110–300 GHz millimetre-wave band. The standard is sold by IEEE, the next entry reproduces its chart.
- Radar Band Letter Designations (from IEEE Standard 521-2019) — D. Kelley, Bucknell University ↗ — one-page chart with the band edges used here
- Speed-Measuring Device Performance Specifications: Across-the-Road Radar Module (DOT HS 810 845) — NHTSA ↗ — the K-band speed-radar frequency 24.150 GHz
- Radio spectrum — Wikipedia ↗ — the NATO letter table (citing the NATO ARFA handbook) and the IEEE HF/VHF/UHF edges from IEEE Std 521-2002, read 7 November 2026
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